flopped straight

[vanHelsing]

UTG + Button are unknown, SB is a known Aggro, plays too many hands (48% Vol.$), but he is not stupid. Actually he is way up in the sessions I had w/ him.

Party Poker 5/10 Hold'em (6 max, 5 handed) converter (http://www.selachian.com/tools/bisonconverter/hhconverter.cgi)

Preflop: Hero is BB with 8/images/graemlins/spade.gif, 6/images/graemlins/spade.gif.
UTG calls, MP folds, Button calls, SB completes, Hero checks.

Flop: (4 SB) 4/images/graemlins/club.gif, 7/images/graemlins/club.gif, 5/images/graemlins/club.gif <font color="blue">(4 players)</font>
<font color="CC3333">SB bets</font>, <font color="CC3333">Hero raises</font>, <font color="CC3333">UTG 3-bets</font>, <font color="CC3333">Button caps</font>, SB calls, Hero calls, UTG calls.

Turn: (10 BB) Q/images/graemlins/spade.gif <font color="blue">(4 players)</font>
<font color="CC3333">SB bets</font>, <font color="CC3333">Hero raises</font>, UTG calls, Button calls, <font color="CC3333">SB 3-bets</font>, Hero calls, UTG calls, Button calls.

River: (22 BB) 3/images/graemlins/spade.gif <font color="blue">(4 players)</font>
<font color="CC3333">SB bets</font>, Hero calls, UTG folds, Button folds.

Final Pot: 24 BB

Results in white below: <font color="white">
SB shows 6c Tc (flush, ten high).
Hero shows 8s 6s (straight, eight high).
Outcome: SB wins 24 BB. </font>

Am I the LAG here?
Do I have to slow down earlier or even fold at some point?